Abstract: A multiple-level memory cell is capable of taking on a plurality of states, with each state being represented by a different value of a physical quantity and being associated with a corresponding logic value. A method for reading the memory cell includes the step of setting an actual physical quantity to a value correlated with the value of the physical quantity corresponding to the state of the memory cell. This step is repeated until the logic value corresponding to the state of the memory cell is determined. A cycle includes the step of setting a component of the logic value to a value which is a function of a range in which the actual physical quantity lies, as determined by comparing the actual physical quantity with at least one reference physical quantity having a predetermined value lying between a minimum value and a maximum value for the actual physical quantity.

Abstract: The invention relates to a driving circuit for row decoding which is also useful in non-volatile memory devices of the multi-level Flash type and the multi-level EPROM type and allows the overall capacitive loads as seen from the program voltage generator and the read/verify voltage generator, to be drastically reduced without involving segmentation of the decoding circuit.

Abstract: In a storage device of the multi-level type, comprising a plurality of memory cells addressable through an address input each cell being adapted for storing more than one binary information element in a MOS transistor which has a control gate, and a floating gate for storing electrons to modify the threshold voltage of the transistor, and comprising a circuit enabling a Direct Memory Access (DMA) mode for directly accessing the memory cells from outside the device, the memory cells are programmed in the direct memory access mode by controlling, from outside the device, the amount of charge stored into the floating gate of each transistor.

Abstract: A timing circuit for reading from a device comprising multi-level non-volatile memory cells, which circuit comprises a single programmable delay block connected to an input terminal for memory address line transition signals. The delay block drives a counter which feedback controls the discharge through a combinational logic circuit connected to the output terminal of the programmable delay block. A logic output circuit, connected to the output terminal of the delay block and to the counter, generates the timing signals.

Abstract: A read circuit for semiconductor memory cells, comprising first and second active elements coupled to a supply line via at least a first switch, wherein the first and second active elements are respectively connected, at first and second circuit nodes, respectively, to a first transistor through which the active elements are coupled to a ground. These first and second circuit nodes are also connected to ground through first and second capacitive elements, respectively, each having a switch connected in parallel to the capacitive element.

Abstract: A staircase adaptive voltage generator circuit comprising a first capacitor connected between a first voltage reference and an output operational amplifier, through first and second switches, respectively. The terminals of the capacitor are also connected to a second voltage reference through third and fourth switches, respectively. A second capacitor, in series with a fifth switch, is connected in parallel to the first capacitor.

Abstract: A read circuit for semiconductor memory cells, comprising first and second active elements coupled to a supply line via at least a first switch, wherein the first and second active elements are respectively connected, at first and second circuit nodes, respectively, to a first transistor through which the active elements are coupled to a ground. These first and second circuit nodes are also connected to ground through first and second capacitive elements, respectively, each having a switch connected in parallel to the capacitive element.

Abstract: Reading circuit for multilevel non-volatile memory cell devices having, for each cell to be read, a selection line with which is associated a load and a decoupling and control stage with a feedback loop which stabilizes the voltage on a circuit node of the selection line. To this node are connected a current replica circuit which are controlled by the feedback loop. These include loads and circuit elements homologous to those associated with the selection line of the memory cell and have an output interface circuit for connection to current comparator circuit.

Abstract: A voltage step-up circuit with regulated output voltage, comprises a voltage divider and a current-absorption circuit connected between the output terminal of the circuit and ground. A control circuit connected to the divider drives the switching of the current-absorption circuit.

Abstract: A page-mode semiconductor memory device comprises a matrix of memory cells arranged in rows and columns, each row forming a memory page of the memory device and comprising at least one group of memory cells, memory page selection means for selecting a row of the matrix, and a plurality of sensing circuits each one associated with a respective column of the matrix. The memory cells are multiple-level memory cells which can be programmed in a plurality of c=2b(b>1) programming states to store b information bits, and the sensing circuits are serial-dichotomic sensing circuits capable of determining, in a number b of consecutive approximation steps, the b information bits stored in the memory cells, at each step one of said b information bits being determined, said at least one group of memory cells of a row forming a number b of memory words of a memory page.

Abstract: A method for sensing multiple-levels non-volatile memory cells which can take one programming level among a plurality of m=2.sup.n (n>=Z) different programming levels, provides for biasing a memory cell to be sensed in a predetermined condition, so that the memory cell sinks a cell current with a value belonging to a discrete set of m distinct cell current values, each cell current value corresponding to one of said programming levels.

Abstract: A read circuit for memory cells which has two legs, each having, in cascade with one another, an electronic switch (SW1,SW2), an active element (T1,T2), feedback connected to the active element in the other leg to jointly produce a voltage amplifier, and a switch load element (L1,L2). Each active element is driven through a high-impedance input circuit element.

Abstract: A voltage regulator for electrically programmable, non-volatile memory devices has an output terminal connected to a power supply line for programming the state of at least one memory element through at least one selection circuit. At least first and second resistive elements are connected between first and second terminals of a voltage supply. At least a first circuit is matched to the at least one selection circuit, and the first circuit is coupled serially with the resistive elements between the two terminals of the voltage supply. At least one control current generator is connected between one of the first and second voltage supply terminals and a node linking to one of the resistive elements, and the current of the controlled current generator is controlled to be a function of current through the at least one selection circuit. An operational amplifier has an inverting input and a non-inverting input, and the non-inverting input is connected to a node linking to at least one of the resistive elements.

Abstract: A serial dichotomic method for sensing multiple-level non-volatile memory cells which can take one of m=2.sup.n (n>=2) different programming levels, provides for biasing a memory cell to be sensed in a predetermined condition, so that the memory cell sinks a cell current with a value belonging to a plurality of m distinct cell current values, and for: a) comparing the cell current with a reference current which has a value comprised between a minimum value and a maximum value of said plurality of m cell current values, thus dividing said plurality of cell current values into two sub-pluralities of cell current values, and determining the sub-plurality of cell current values to which the cell current belongs; b) repeating the step a) until the sub-plurality of cell current values to which the cell current belongs comprises only one cell current value, which is the value for the current of the memory cell to be sensed.

Abstract: A device for reading memory cells, wherein the device contains two branches, wherein each branch comprises, connected in cascade, an electronic switch, an active element reactively connected to the active element of the other branch, so as to form a voltage amplifier. Each active element is controlled by means of a high impedance circuit element. A microswitch connects the two branches together is inserted between the two active elements.

Abstract: A sensing circuit for serial dichotomic sensing of multiple-level memory cells which can take one programming level among a plurality of m=2.sup.n (n>=2) different programming levels, comprises biasing means for biasing a memory cell to be sensed in a predetermined condition, so that the memory cell sinks a cell current with a value belonging to a plurality of m distinct cell current values, each cell current value corresponding to one of the programming levels, a current comparator for comparing the cell current with a reference current generated by a variable reference current generator, and a successive approximation register supplied with an output signal of the current comparator and controlling the variable reference current generator.

Abstract: A circuit for generating positive and negative boosted voltages, comprising first and second voltage booster circuits, respectively for positive and negative voltages, which have output terminals interconnected at a common node. It comprises two tristate logic gate circuits for coupling said voltage booster circuits to a positive supply voltage generator and additional tristate logic gate circuits for driving the phases of charge pump circuits incorporated into the booster circuits. This voltage generating circuit may be integrated in single-well CMOS technology.

Abstract: The switching noise generated by a data output buffer is greatly reduced by "precharging" the output node to an intermediate voltage during a system's "dead" time. This is done with a precharging output current pulse having a constant time derivative during a first time interval and a constant time derivative of opposite sign during a second time interval, before performing the actual switching with an output current having a constant time derivative, during a third time interval. The partial precharging with a controlled, triangular-shaped, output current pulse, avoids any abrupt change of output current and thus limits switching noise. The buffer of the invention is particularly useful in high-speed memory devices.

Abstract: A signal generator which includes two matched ring oscillators, and feedback gates which cross-couple each ring oscillator to the other. That is, in each oscillator, a first node gates a coupling transistor which connects a second node (complementary to the first node) across to drive the first node of the other oscillator.

Abstract: A fast capacitive-load driving circuit for driving output nodes on an integrated circuit. This circuit reduces noise interference caused by parasitic inductance by lowering the inductance voltage on the power supply lines during the switching process. This invention includes a voltage ramp, a voltage-to-current converter, and an output buffer having at least one pull-down transistor. A further embodiment includes an output buffer possessing a pull-down and a pull-up transistor.